How to stop Blender from making the CPU overheat?
Edit, The original question was "How to pause between rendering frames", if my answer seems out of place.

Yes, to sleep in-between rendering frames you can use a Python script to add a render_post handler, it will sleep in-between rendering frames of an animation.

import time
def sleep(scene, seconds=2.0):
    print("Sleep start")
    time.sleep(seconds)
    print("Sleep stop")

import bpy
bpy.app.handlers.render_post.append(sleep)


If you want this to always be enabled, copy it into render_sleep.py and put it in blenders scripts/startup/ path.



Note: I have serious doubts about this as being a GOOD solution to the problem you describe, a frame that takes a long time to render could overheat your system - so relying on sleeping between frames seems very precarious, on Linux there are tools to throttle process CPU use, check on nice and cpulimit (if under-clocking or better cooling isnt an option).